The present invention relates to installations for treating at least one fluid, comprising at least one mass of particulate material through which the fluid circulates in a horizontal axial direction.
When gases are to be produced, separated or purified, use may be made of adsorption methods. These generally employ several adsorbers filled with materials which are selectively adsorbent towards at least one of the constituents of the feed stream. There are 2 main types of adsorbers, axial bed adsorbers and radial bed adsorbers.
Axial bed adsorbers provide an economical solution to the problems of holding the bed and of dead volumes. By contrast, when high flow rates are used the pressure drops and problems of attrition become limiting for this technology. This is because in order to push back the fluidization limit, which ultimately leads to the granules of adsorbent being destroyed, the main solutions are:                to increase the diameter of the adsorber (with a maximum diameter that has to be adhered to because of transport considerations), which entails reducing the length of the bed, the disadvantage of this being that it presents problems of distribution upstream and downstream of the adsorbent, of increasing dead volumes and of reducing the thickness of the beds thus making the methods more sensitive to the unevenness of the surface of the bed of adsorbent,        to add adsorbers in order to split the flow passing through the beds,        to increase the size of the beads of adsorbent, although this is to the detriment of the adsorption dynamics and therefore the performance of the unit, and        to add weight to the upper part of the adsorbent, for example using metal beads separated from the adsorbent by a flexible grating.        
These last 2 solutions allow the theoretical limit of attrition in an axial configuration only to be pushed back a little.
It will be noted that present day axial adsorber geometries employed include the “upright bottle” and the “lying-down bottle” geometries, both with the gas circulating vertically through the adsorbent bed. While the latter geometry offers a larger bore sectional area than the former, it is nonetheless penalized by poor distributions, notably at the edges of the adsorber, and greater dead volumes.
A radial bed adsorber allows pressure drops to be limited without increasing the radius of the adsorber because it offers a bore sectional area that is increased for a given volume of adsorber and is theoretically not subject to any limit in terms of attrition. The bed of adsorbent is generally suspended between vertical perforated gratings suspended from the top. The appearance of empty volumes at the top of the beds of adsorbent can be prevented either by a cone system that adheres to the angle of heaping (essentially used in TSA) as described in U.S. Pat. No. 5,882,385 or by a membrane on which metal or ceramic beads rest, which is the system currently used in O2 VSA. The major disadvantages with this radial technology are an increase in dead volumes and a high cost of manufacture.